1. Field of the Invention
The present invention relates to a high-speed axial-flow gas laser generator, and, specifically, to a high-speed axial-flow gas laser generator provided with a nozzle which imparts a spiral rotary motion to the gas flow in the laser tube.
2. Description of the Related Art
As high-speed axial-flow gas laser generators, there are the transverse inflow type which employs a system wherein the laser gas flows into the laser tube in a transverse direction relative to the laser, tube, and the inclined inflow type wherein the laser gas flows into the laser tube at a predetermined angle relative to the laser tube.
Generally, in the transverse inflow type a ceramic nozzle is mounted at right angles to the laser tube in the laser gas inflow section of the laser tube, and an anode pin is provided in the interior of this ceramic nozzle. A ring-shaped cathode is mounted in the laser gas discharge section of the laser tube. A high voltage power source is connected between the cathode and the anode pin.
In the inclined inflow type of high-speed axial-flow laser gas generator, a ring-shaped anode and a ceramic nozzle are generally mounted on the laser gas inflow side of the laser tube at a predetermined distance with an inclined slot therebetween. A ring-shaped cathode is mounted on the laser gas discharge side of the laser tube. A high voltage power source is connected between the cathode and the anode.
In the transverse inflow type of high-speed axial-flow laser gas generator, because the laser gas is bent at a right angle when it flows into the laser tube an undulation phenomenon is produced close to the laser gas inflow section of the laser tube. This causes the upstream gas flow to become unstable so that the plasma generated by the electric discharge is also unstable. In addition, in the area close to the downstream cathode the laser gas is expanding and is flowing at a high speed, so that the Reynolds number of the laser gas is in the turbulent flow area and turbulent flow occurs. This turbulent flow acts to break up a turbulent flow of larger scale which appears locally uniform within the laser tube. Accordingly, because the laser gas flow fluctuates from the lack of turbulent flow of larger scale in the laser gas, the generation of plasma is unstable. This fact becomes strikingly obvious when the discharge current increases.
In addition, in the inclined inflow type of high-speed axial-flow laser gas generator, because the anode is ring-shaped, the discharge spot moves on a ring, or grows, and a uniform electric discharge is difficult to obtain. In addition, in the same way as in the previous example, because the gas flow close to the downstream cathode fluctuates, the plasma generation is unstable. This becomes strikingly obvious when the electric discharge current increases.